自引用表查询

Question

I have a table called commitments where the primary key is commit_no and a self referencing column in called commit_rollup_no . My goal is to be able to pull back all the referenced tabled based on the highest commit_no .

Example

commit_no | commit_rollup_no
---------------------------
1           null
2           1
3           1
4           2
5           3
6           5
7           6

Desired Result:

for all commitments that rollup to commit_no 1

2,3,4,5,6,7

for all commitments that rollup to commit_no 2

4

for all commitments that rollup to commit_no 3

5,6,7

I was wondering how someone with more experiencing with self-referring tables might tackle this query. In some cases it might go 100 levels deep and the requirement is to get all the associated commitments back.

Answer 1

Would this work out for you?

SELECT `commit_no`,
       (SELECT Group_concat(`commit_no`)
        FROM   `commits` `c`
        WHERE  `c`.`commit_rollup_no` = `com`.`commit_no`) AS `SubCommits`
FROM   `commits` AS `com`

SQL Fiddle

MySQL 5.6 Schema Setup :

CREATE TABLE commits
    (`commit_no` int, `commit_rollup_no` int)
;

INSERT INTO commits
    (`commit_no`, `commit_rollup_no`)
VALUES
    (1, 0),
    (2, 1),
    (3, 1),
    (4, 2),
    (5, 3),
    (6, 5),
    (7, 6)
;

Query 1 :

SELECT `commit_no`, (SELECT GROUP_CONCAT(`commit_no`) FROM `commits` `c` WHERE `c`.`commit_rollup_no` = `com`.`commit_no`) AS `SubCommits` FROM `commits` AS `com`

Results :

+-----------+------------+
| commit_no | SubCommits |
+-----------+------------+
|         1 |        2,3 |
|         2 |          4 |
|         3 |          5 |
|         4 |     (null) |
|         5 |          6 |
|         6 |          7 |
|         7 |     (null) |
+-----------+------------+

Answer 2

CREATE DEFINER=`IDPAdmin`@`%` FUNCTION `CommitChildren`(ParentCommit INT) RETURNS varchar(1024) CHARSET latin1
DETERMINISTIC
BEGIN

DECLARE rv,q,queue,queue_children VARCHAR(1024);
DECLARE queue_length,front_id,pos INT;

SET rv = '';
SET queue = ParentCommit;
SET queue_length = 1;

WHILE queue_length > 0 DO
    IF queue_length = 1 THEN
    SET front_id = queue;
        SET queue = '';
    ELSE
         SET front_id = SUBSTR(queue,1,LOCATE(',',queue)-1);
    SET pos = LOCATE(',',queue) + 1;
    SET q = SUBSTR(queue,pos);
    SET queue = q;
END IF;
    SET queue_length = queue_length - 1;

    SELECT IFNULL(qc,'') INTO queue_children
    FROM (SELECT GROUP_CONCAT(commit_no) qc
    FROM commitments WHERE commit_rollup_no = front_id) A;

    IF LENGTH(queue_children) = 0 THEN
        IF LENGTH(queue) = 0 THEN
            SET queue_length = 0;
        END IF;
    ELSE
        IF LENGTH(rv) = 0 THEN
            SET rv = queue_children;
        ELSE
            SET rv = CONCAT(rv,',',queue_children);
        END IF;
        IF LENGTH(queue) = 0 THEN
            SET queue = queue_children;
        ELSE
            SET queue = CONCAT(queue,',',queue_children);
        END IF;
        SET queue_length = LENGTH(queue) - LENGTH(REPLACE(queue,',','')) + 1;
    END IF;
END WHILE;

RETURN rv;

END